Superparamagnetic nanoparticle-based nanobiomolecular detection in a microfluidic channel

A novel biomolecular detection principle based on the magnetic force in a microfluidic channel or a lab-on-a-chip was developed. The microbeads conjugated with superparamagnetic nanoparticles can only switch their own fluidic path in a microfluidic channel due to magnetic fields. To investigate the migration behavior of microbeads, the sample and buffer solutions were injected in the same flow rate to make a laminar flow. The streptavidin conjugated superparamagnetic nanoparticles were reacted with biotinylated fluorescent microbeads. The velocities of microbeads were observed in a microchannel by the CCD camera on an inverted microscope. As expected, the movements of microbeads conjugated with superparamagnetic nanoparticles were dependent upon the concentrations of superparamagnetic nanoparticles. This detection scheme can be useful for various assay systems and multiplexed biological analysis systems using encoded microbeads.